The overall goal of this proposed research is to obtain a relatively detailed description of the organization of ribonucleoprotein (RNP) complexes associated with specific nuclear RNA molecules. HeLa cells productively infected with human adenovirus type 2 will be used for this stdy because transcription and post-transcriptional processing of adenovirus RNA are relatively well understood and transcripts of adenovirus are highly abundant in the cell nucleus at later stages of infection. Although Georgeiv and coworkers reported in 1972 that adenovirus-specific transcripts were present in nuclear RNA-protein complexes, up until now this potentially incisive system has not been utilized further for the study of ribonucleoprotein structure. Initial experiments will be directed towards the characterization of isolated nuclear RNP complexes containing adenovirus RNA in order to better establish their similarity to RNP complexes containing cellular heterogeneous nuclear RNA (hnRNA). Further experiments will focus on the possible relationship between the nucleotide sequence of adenovirus RNA and the sites of protein-RNA interactions. This relationship will be examined by digesting RNA in nuclear complexes with nuclease, isolating RNA sequences protected from digestion by bound proteins, and characterizing these protected regions of RNA by hybridization to adenovirus DNA. The RNP structure associated with particular nuclear RNA transcripts or regions of RNA molecules will be similarly probed by hybridizing digested RNA to specific DNA restriction fragments of the adenovirus genome. The results of this study will provided detailed information regarding the organization of Rna and proteins on specific nuclear transcripts. This information will contribute to a more precise understanding of mechanisms regulating the replication of adenovirus and the nuclear processing of primary gene transcripts in normal, proliferating animal cells.